Electromechanical actuators are used in a wide variety of applications to produce motion in response to an electric current.
In many situations where actuators are employed, for example in aerospace or marine applications, space is limited. It would therefore be advantageous to provide a more compact actuator.
In general, the utility of a particular actuator in a given scenario will be determined by its force density, that is to say the amount of force the actuator can generate in proportion to its mass. It would therefore be advantageous to provide an actuator with an increased force density.
Many applications in which actuators are used require the generation of motion in more than one degree of freedom. Typically, in order to produce multiple degree of freedom motion, a plurality of single degree of freedom actuators are used, with each individual actuator providing movement in its own respective degree of freedom. Actuator systems which are designed in this manner are relatively bulky. Moreover, the complexity (both mechanically and in terms of control) of the system may also increase manufacturing cost and/or reduce reliability.
One particular application of actuators is in active vibration control, where an actuator may be used to exert a force on a structure in order to reduce vibration of the structure. The force may be generated by moving a proof-mass. Vibrational motion may occur in multiple degrees of freedom, and may involve movement in all six degrees of freedom. It is therefore desirable to have actuator systems capable of producing multiple degrees of freedom force to reduce the effects of such vibration. Typically this has required multiple actuators (as discussed above) and multiple proof-masses, with each actuator moving its respective proof-mass. Active vibration systems designed in this manner are generally bulky and have relatively low force density.
The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved actuator, particularly an improved actuator for use in active vibration control.